diff --git a/src/config.ts b/src/config.ts
index aac43af..c307ef2 100644
--- a/src/config.ts
+++ b/src/config.ts
@@ -18,15 +18,72 @@ type Config = {
 };
 
 import uncheckedConfig from '../config.json' assert { type: 'json' };
+import log from '@/utils/log.js';
+
+class Type<T> {
+	public static readonly string = new Type<string>('string');
+	public static readonly boolean = new Type<boolean>('boolean');
+
+	public readonly name: string;
+
+	private constructor(name: string) {
+		this.name = name;
+	}
+
+	check(value: unknown): value is T {
+		return typeof value == this.name;
+	}
+}
+
+function checkProperty<K extends keyof Config>(config: Object, key: K, type: Type<Config[K]>): config is { [J in K]: Config[K] } {
+	const result = key in config && type.check(config[key as string]);
+	if (!result) {
+		log(`config.json: Property ${key}: ${type.name} required`);
+	}
+	return result;
+}
+
+function checkOptionalProperty<K extends keyof Config>(config: Object, key: K, type: Type<Config[K]>): config is { [J in K]?: Config[K] } {
+	if (!(key in config)) {
+		return true;
+	}
+	const result = type.check(config[key as string]);
+	if (!result) {
+		log(`config.json: The type of property ${key} must be ${type.name}`);
+	}
+	return result;
+}
+
+function setProperty<K extends keyof Config>(config: Object, key: K, value: Config[K]): asserts config is { [L in K]: Config[K] } {
+	(config as { [L in K]?: Config[K] })[key] = value;
+}
 
 function validate(config: unknown): Config {
-	// TODO: as を使わずにしっかりと検証を行う
-	return config as Config;
+	if (!(config instanceof Object)) {
+		log('config.json: Root object required');
+	} else if (
+		checkProperty(config, 'host', Type.string) &&
+		checkOptionalProperty(config, 'serverName', Type.string) &&
+		checkProperty(config, 'i', Type.string) &&
+		checkOptionalProperty(config, 'master', Type.string) &&
+		checkProperty(config, 'keywordEnabled', Type.boolean) &&
+		checkProperty(config, 'reversiEnabled', Type.boolean) &&
+		checkProperty(config, 'notingEnabled', Type.boolean) &&
+		checkProperty(config, 'chartEnabled', Type.boolean) &&
+		checkProperty(config, 'serverMonitoring', Type.boolean) &&
+		checkOptionalProperty(config, 'checkEmojisEnabled', Type.boolean) &&
+		checkOptionalProperty(config, 'checkEmojisAtOnce', Type.boolean) &&
+		checkOptionalProperty(config, 'mecab', Type.string) &&
+		checkOptionalProperty(config, 'mecabDic', Type.string) &&
+		checkOptionalProperty(config, 'memoryDir', Type.string)
+	) {
+		setProperty(config, 'wsUrl', config.host.replace('http', 'ws'));
+		setProperty(config, 'apiUrl', config.host + '/api');
+		return config;
+	}
+	throw new TypeError('config.json has an invalid type');
 }
 
 const config = validate(uncheckedConfig);
 
-config.wsUrl = config.host.replace('http', 'ws');
-config.apiUrl = config.host + '/api';
-
 export default config;